Naphthalimide derivatives

ABSTRACT

Naphthalimide derivatives of the general formula ##STR1## where R 1  is hydrogen or C 1  - to C 4  -alkyl, 
     R 2  is nitrile or a radical containing a carbonyl group or an acetalized carbonyl group and 
     R 3  and R 4  are unsubstituted or substituted alkyl. 
     The compounds are excellent optical brighteners, especially for synthetic fibers.

The present invention relates to a compound of the general formula I##STR2## where R¹ is hydrogen or C₁ - to C₄ -alkyl,

R² is a radical of the formula ##STR3## R³ and R⁴ independently of oneanother are C₁ - to C₄ -alkyl, β-hydroxyethyl, β-hydroxypropyl, β-C₁ -to C₄ -alkoxyethyl or β-C₁ - to C₄ -alkoxypropyl,

R is C₁ - to C₄ -alkyl,

R⁵ is hydrogen, C₁ - to C₄ -alkyl, hydroxyl, C₁ - to C₈ -alkoxy,β-hydroxyethoxy, β-C₁ - to C₄ -alkoxyethoxy, β-hydroxypropoxy, β-C₁ - toC₄ -alkoxypropoxy, amino, hydrazino, C₁ - to C₄ -alkylamino, or C₁ - toC₄ -dialkylamino which are unsubstituted or substituted by hydroxyl orby C₁ - to C₄ -alkoxy, pyrrolidino, piperidino, morpholino, piperazino,N-methylpiperazino, β-dialkylamino- or -trialkylammonium-ethylamino orβ- or γ-dialkylamino- or -trialkylammonium-propylamino and

X is --CH₂ --CH₂ --, --CH₂ CH₂ CH₂ --, ##STR4##

C₁ - to C₄ -alkyl radicals R, R¹, R³, R⁴ and R⁵ are n- or i-propyl, n-or i-butyl and, preferably, methyl or ethyl.

Alkoxyalkyl radicals R³ and R⁴ are, for example, C₂ H₄ OC₂ H₅, C₂ H₄ OC₃H₇, C₂ H₄ OC₄ H₉, ##STR5## and preferably C₂ H₄ OCH₃.

Specific examples of radicals R⁵, in addition to those alreadymentioned, are: ##STR6##

A compound of the formula I may be prepared by reacting a compound ofthe formula II ##STR7## with a compound of the formula

    R.sup.3 OMe and/or R.sup.4 OMe

where Me is preferably an alkali metal. The use of mixtures of R³ OMeand R⁴ OMe is preferred.

Compounds of the formula I, where R² is COR⁵, R⁵ being hydrogen, C₁ - toC₄ -alkyl or hydroxyl, are obtained from the corresponding acetals,ketals or esters by hydrolysis.

The reactions are known in principle; details may be found in theExamples, where parts and percentages are by weight, unless statedotherwise.

The compounds of the formula I may be used as optical brighteners forsynthetic and cellulosic fibers, especially for polyester and acetatefibers, on which high degrees of whiteness are obtained with smallamounts of brightener. The good lightfastness and the greenish whitetint also deserve special mention.

Some of the compounds can also be used for mass brightening.

Particularly important compounds are those of the formula Ia ##STR8##where B is -CHO, ##STR9## and R, R¹, R³ and R⁴ have the stated meanings.B is preferably CHO.

Particularly preferred meanings of R³ and R⁴ are methyl and ethyl.Furthermore, compounds where R³ and R⁴ are different are preferred.

EXAMPLE 1

87 parts of 4,5-dichloro-N-(1',1'-dimethoxyprop-2'-yl)-naphthalimide,630 parts of methanol and 78 parts of butyltriglycol are mixed. 146parts of a 30% strength sodium methylate solution in methanol are addeddropwise at 50°-60° C., whilst stirring, and the mixture is then stirredunder reflux for 12 hours. When it has cooled, the product is filteredoff and washed with 160 parts of methanol and 1,000 parts of water. 80parts (96% yield) of the compound of the formula ##STR10## of meltingpoint 178°-179° C. are obtained.

4,5-Dichloro-N-(1',1'-dimethoxyprop-2'-yl)-naphthalimide may be obtainedby reacting 4,5-dichloronaphthalic anhydride with2-amino-propanaldimethylacetal.

The following compounds were prepared analogously:

    __________________________________________________________________________                                        Melting                                   Ex-                                 point                                                                              Yield                                ample                                                                             R.sup.1                                                                           R.sup.2      R.sup.3                                                                               R.sup.4                                                                              (°C.)                                                                       (%)                                  __________________________________________________________________________    2   CH.sub.3                                                                          CH(OCH.sub.3).sub.2                                                                       C.sub.2 H.sub.5                                                                       C.sub.2 H.sub.5                                                                       182-86                                                                             99                                   3   CH.sub.3                                                                          CH(OCH.sub.3).sub.2                                                                       C.sub.4 H.sub.9                                                                       C.sub.4 H.sub.9                                                                       154-58                                                                             97                                   4   CH.sub.3                                                                          CH(OCH.sub.3).sub.2                                                                       C.sub.2 H.sub.4 OH                                                                    C.sub.2 H.sub.4 OH                                                                    179-83                                                                             69                                   5   CH.sub.3                                                                          CH(OCH.sub.3).sub.2                                                                       C.sub.2 H.sub.4 OC.sub.2 H.sub.5                                                      C.sub.2 H.sub.4 OC.sub.2 H.sub.5                                                      102-06                                                                             90                                   6   CH.sub.3                                                                          CH(OCH.sub.3).sub.2                                                                       70% CH.sub.3                                                                          70% CH.sub.3                                                                          185-88                                                                             92                                                       30% C.sub.2 H.sub.5                                                                   30% C.sub.2 H.sub.5                               7   C.sub.2 H.sub.5                                                                    ##STR11##  CH.sub.3                                                                              CH.sub.3                                                                              213-16                                                                             98                                   __________________________________________________________________________

EXAMPLE 8

100 parts of 4,5dimethoxy-N-(1',1'-dimethoxyprop-2'-yl)-naphthalimideare added to a solution of 680 parts of N,N-dimethylformamide, 30 partsof water and 2 parts of p-toluenesulfonic acid. The reaction mixture isstirred for 8 hours at 120°-130° C. The product is precipitated with1,000 parts of water, filtered off and dried. 87 parts (100% yield) ofthe compound of the formula ##STR12## are obtained; afterrecrystallization from N,N-dimethylformamide, the compound melts at275°-278° C.

The following compounds were prepared analogously:

    __________________________________________________________________________                                 Melting                                          Ex-                          point                                                                              Yield                                       ample                                                                             R.sup.1                                                                           R.sup.2                                                                            R.sup.3 R.sup.4 (°C.)                                                                       (%)                                         __________________________________________________________________________     9  CH.sub.3 --                                                                       --CHO                                                                              --C.sub.2 H.sub.5                                                                     --C.sub.2 H.sub.5                                                                     261-63                                                                             91                                          10  CH.sub.3 --                                                                       --CHO                                                                              --C.sub.4 H.sub.9                                                                     --C.sub.4 H.sub.9                                                                     165-67                                                                             92                                          11  CH.sub.3 --                                                                       --CHO                                                                              --C.sub.2 H.sub.4 OH                                                                  --C.sub.2 H.sub.4 OH                                                                  242-45                                                                             98                                          12  CH.sub.3 --                                                                       --CHO                                                                              --C.sub.2 H.sub.4 OC.sub.2 H.sub.5                                                    --C.sub.2 H.sub.4 OC.sub.2 H.sub.5                                                    188-90                                                                             192                                         13  CH.sub.3                                                                          --CHO                                                                              70% CH.sub.3 --                                                                       70% CH.sub.3 --                                                                       233-35                                                                             100                                                      30% C.sub.2 H.sub.5 --                                                                30% C.sub.2 H.sub.3 --                                   14  C.sub.2 H.sub.5 --                                                                --CHO                                                                              --CH.sub.3                                                                            --CH.sub.3                                                                            262-64                                                                             90                                          __________________________________________________________________________

EXAMPLE 15

42 parts of4,5-dichloro-N-(3'-butyl-2',2'-ethanediolketal)-naphthalimide, 316 partsof methanol and 39 parts of butyltriglycol are mixed. 77 parts of a 30%strength sodium methylate solution in methanol are added dropwise whilststirring under reflux. After stirring for 12 hours, 11 parts ofpotassium tertiary butylate are added and stirring under reflux iscontinued for 8 hours. When the mixture has cooled, the product isfiltered off and washed with 160 parts of methanol and 1,500 parts ofwater. 41 parts (100% yield) of the compound of the formula ##STR13## ofmelting point 192°-194° C. are obtained.

4,5-Dichloro-N-(3'-butyl-2',2'-ethanediolketal)naphthalimide isobtainable by reacting 4,5-dichloronaphthalic anhydride with3-aminobutanone-2-ethanediolketal.

The following compounds were prepared analogously:

    __________________________________________________________________________                                    Melting                                       Ex-                             point                                                                              Yield                                    ample                                                                             R.sup.1                                                                           R.sup.2         R.sup.3                                                                           R.sup.4                                                                           (°C.)                                                                       (%)                                      __________________________________________________________________________    16  CH.sub.3                                                                           ##STR14##      CH.sub.3                                                                          CH.sub.3                                                                          260-62                                                                             40                                       17  CH.sub.3                                                                           ##STR15##      CH.sub.3                                                                          CH.sub.3                                                                          198-99                                                                             67                                       18  CH.sub.3                                                                           ##STR16##      CH.sub.3                                                                          CH.sub.3                                                                          166-68                                                                             70                                       19  CH.sub.3                                                                           ##STR17##      CH.sub.3                                                                          CH.sub.3                                                                          195-97                                                                             71                                       20  CH.sub.3                                                                           ##STR18##      CH.sub.3                                                                          CH.sub.3                                                                          215-17                                                                             56                                       21  CH.sub.3                                                                           ##STR19##      CH.sub.3                                                                          CH.sub.3                                                                          205-06                                                                             70                                       22  CH.sub.3                                                                           ##STR20##      CH.sub.3                                                                          CH.sub.3                                                                          268-71                                                                             100                                      __________________________________________________________________________

EXAMPLE 23

22 parts of4,5-dimethoxy-N-(3'-butyl-2',2'-ethanediolketal)-naphthalimide are addedto a solution of 24 parts of N,N-dimethylformamide and 265 parts of 4 Nhydrochloric acid. The reaction mixture is stirred for 40 hours at 100°C. When it has cooled, the product is filtered off and washed acid-freewith water. 18 parts (92% yield) of the compound of the formula##STR21## are obtained; after recrystallization fromN,N-dimethylformamide, the compound melts at 281°-284° C.

EXAMPLE 24

32 parts of 4,5-dichloro-N-(2'-propionic acid methylester)-naphthalimide are introduced into 276 parts of methanol and 34parts of butyltriglycol. 60 parts of a 30% strength sodium methylatesolution in methanol are added dropwise under reflux. Refluxing iscontinued for 12 hours. After the mixture has cooled, the product isfiltered off and washed with 160 parts of methanol and 1,000 parts ofwater. 31 parts (100% yield) of the compound of the formula ##STR22##are obtained; after recrystallization from N,N-dimethylformamide, thecompound melts at 219°-222° C.

4,5-Dichloro-N-(2'-propionic acid methyl ester)naphthalimide may beobtained by reacting 4,5-dichloronaphthalic anhydride with methyl2-aminopropionate hydrochloride.

The following was prepared analogously:

    ______________________________________                                                                            Melting                                   Ex-                                 point  Yield                              ample R.sup.1                                                                              R.sup.2    R.sup.3                                                                             R.sup.4                                                                             (°C.)                                                                         (%)                                ______________________________________                                        25    H      --COOC.sub.2 H.sub.5                                                                     --C.sub.2 H.sub.5                                                                   --C.sub.2 H.sub.5                                                                   >300   100                                ______________________________________                                    

EXAMPLE 26

16 parts of 4,5-dimethoxy-N-(2'-propanaloxime)naphthalimide are added to264 parts of thionyl chloride. The mixture is stirred for 1.25 hours at80° C. and, when it has cooled, is stirred into 1,500 parts of icewater. Stirring is continued for 1 hour and the product is filtered offand washed with 2,000 parts of water. 15 parts (97% yield) of thecompound of the formula ##STR23## are obtained; after recrystallizationfrom N,N-dimethylformamide, the product melts at >300° C.

4,5-Dimethoxy-N-(2'-propanaloxime)-naphthalimide may be obtained byreacting 4,5-dimethoxy-N-(2'-propanal)naphthalimide with hydroxylaminehydrochloride.

We claim:
 1. A naphthalimide having the formula: ##STR24## wherein R' ishydrogen or C₁ - to C₄ -alkyl; and,R³ and R⁴ independently of oneanother are C₁ - to C₄ -alkyl, β-hydroxyethyl, β-hydroxypropyl, β-C₁ -to C₄ -alkoxyethyl or β-C₁ - to C₄ -alkoxypropyl.
 2. The compound asclaimed in claim 1, wherein R³ and R⁴ are identical or different and aremethyl or ethyl.
 3. The compound as claimed in claim 2, wherein R¹ ismethyl.